docs: def start(self):
          '''
          Startup the kafka consumer.
          '''
          log.debug('Creating the consumer using the bootstrap servers: %s and the group ID: %s',
                    self.bootstrap_servers,
                    self.group_id)
          try:
              self.consumer = kafka.KafkaConsumer(bootstrap_servers=self.bootstrap_servers,
                                                  group_id=self.group_id)
          except kafka.errors.NoBrokersAvailable as err:
              log.error(err, exc_info=True)
              raise ListenerException(err)
          log.debug('Subscribing to the %s topic', self.topic)
          self.consumer.subscribe(topics=[self.topic])